Hey there! Great question - no one wants to miss a message when they have to miss a call. Generally speaking, you can set up Voicemail by following the steps here. I'm also a little concerned about the error you're getting with Visual Voicemail - can you try that again once your basic voicemail box is already created? Just to make sure, were you using an LG V20, or an LG Stylo?
Let me know if you're able to follow those voicemail steps and if that gets Visual Voicemail authorized for you!
Hi again! Just wanted to drop by and make sure you'd been able to get your voicemail working. How is everything going for you?